It’s far, far more likely that private property will ban guns- unless it’s some form of ultra exclusive club that deals with security all the time. They’re also banned from any school as a matter of federal law.

Those places have to worry about their own safety and liability. While difficult to enforce- especially if some one is planning on ignoring it- the policy provides some of the few measures of prevention. The last thing anybody wants is to be in the middle of a “white man shot black kid over a ham” unless the protective agents are cops (secret service, gobenatorial details, etc)

As for preparedness, it’s more like “oh they have 9mm pistols, we’ll be wearing body armor.” Or “oh they have ars we’ll wear more protective body armor”

Protecting somebody is about stopping them before they ever get to be a problems. The body guards themselves aren’t there to stop the bad guy, they’re there for when everything else fails- to get the client the fuck out of there.